<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>content动态数据获取</title>
  <style type="text/css">
    p::before{
      content: attr(data-username);
    }
  </style>
</head>
<body>
  <p data-username="Chocolate">,欢迎您的来访!</p>
</body>
</html>